The invention relates to a method for handling workpieces which are sterile at least in regions and have a finable inner volume, in which the workpieces are connected to a closure device together with which the workpieces are guided through a plurality of treatment stations, wherein one of the treatment stations is a sterilization unit, and wherein, in at least one of the treatment stations, a treatment member is moved through a Passage opening in the closure device into the inner volume of the workpiece. In particular, the invention relates to a method for handling preforms composed of a thermoplastic material for producing blow molded containers which are sterile at least in regions, and/or to a method for handling containers produced in a blow-molding manner from preforms. The preforms are guided here in particular through a plurality of treatment stations of a blow molding machine, namely at least through a sterilization unit in which the preforms are subjected to a sterilization treatment. Furthermore, said preforms can be guided through a heating unit in which the preforms are conditioned thermally for the blow molding, and/or through a blow molding station in which the preforms are blow molded to form containers, and/or through inlet, discharge and/or transfer star wheels in which the preforms and/or the containers are transported.
The invention furthermore relates to a closure device for handling a workpiece which is sterile at least in regions and has a fillable inner volume, with connecting means for the releasable connection of the workpiece to the closure device, wherein the closure device has a passage opening which is provided with sealing means and through which a treatment member of a treatment station can be moved in a sealed manner into the inner volume of the workpiece. The workpieces here are in particular preforms composed of a thermoplastic material for producing blow molded containers which are sterile at least in regions, and/or containers produced in a blow-molding manner from preforms. The treatment stations belong in particular to a blow molding machine and comprise at least one sterilization unit in which the preforms are subjected to a sterilization treatment, optionally additionally a heating unit in which the preforms are conditioned thermally for the blow molding, and/or additionally a blow molding station in which the preforms are blow molded to form containers, and/or additionally inlet, discharge and/or transfer star wheels in which the preforms and/or the containers are transported.
Finally, the invention relates to a blow molding machine with a closure device and to the use of a closure device and a blow molding machine for carrying out a handling method.
The invention is explained below primarily with reference to the sequences and operations during the blow-molding production of containers, which are sterile at least in regions, from preforms and the subsequent filling of said containers, without the invention and the claims being restricted thereto. In an analogous manner, the invention can also be realized in fillers and closers.
Production of sterile, blow molded containers typically takes place in such a manner that said containers are sterilized after the blow molding thereof and prior to filling, using hydrogen peroxide or other chemicals. It is likewise already known to sterilize the preforms, which are used as the starting product in the blow molding of the containers, by means of radiation, in particular the region of the inner and outer surface of said preforms.
In the case of container molding by the effect of blow molding pressure, preforms composed of a thermoplastic material, for example preforms composed of PET (polyethylene terephthalate) are supplied to different treatment stations within a blow molding machine. A blow molding machine of this type typically has a heating unit and a blow molding unit, in the region of which the previously temperature-conditioned preform is expanded by biaxial orientation to form a container. The expansion takes place with the aid of compressed air which is introduced into the preform to be expanded. The process sequence during such an expansion of the preform is explained in DE-A 43 40 291. However, blow molding machines are also known in which the expansion takes place by feeding in a liquid under a positive pressure, in particular by feeding in the filling material under a positive pressure.
The basic design of a blow molding station operating with compressed air for molding containers is described in DE-A 42 12 583. Possibilities for temperature conditioning of the preforms are explained in DE-A 23 52 926.
Within the blow molding machine, the preforms and the blow molded containers can be transported with the aid of different handling units. The use of conveying mandrels, onto which the preforms are plugged, has proven particularly successful. However, the preforms may also be handled using other handling units. The use of gripping tongs for handling preforms, and the use of expanding mandrels, which can be inserted into the mouth region of the preform for holding the latter, likewise belong to the available constructions.
Handling of containers using transfer wheels is described, for example, in DE-A 199 06 438, in an arrangement of the transfer wheel between a blow molding wheel and a discharge section.
It is also known, for the handling of the preforms, to first of all place the latter onto a carrying device, and then to carry out the handling at the carrying device and the preform carried by the latter. Such a carrying device is explained in DE 196 41 943 A1.
The handling of the blow molded containers generally takes place in the same manner as the handling of the preforms because the handling contours and handling portions provided on the preform for the handling remain unchanged during the blow molding operation and are therefore also available on the blow molded container for handling.
With regard to the blow molding stations used, in which the preforms are formed into containers using a pressurized fluid, various embodiments are known. In the case of blow molding stations which are arranged on rotating transport wheels, a book-like opening capability of the mold carriers may frequently be encountered. However, it is also possible to use mold carriers which are displaceable relative to one another or guided in another manner. In the case of positionally fixed blow molding stations, which are suitable in particular for receiving a plurality of cavities for molding containers, plates which are arranged so as to be mutually parallel are typically used as mold carriers.
In terms of the sterilization of preforms, various methods and devices are known from the prior art. For example, EP-A 1 086 019 A1 describes the sterilization of hot preforms with a hot gaseous sterilization agent. Use is made of separate treatment stations arranged consecutively, namely a first heating module, a sterilization module and a second heating module. The temperature behavior of the preform during the sterilization operation and the uncontrolled leakage of the sterilization agent out of the preform within the heating system are disadvantageous here. There is furthermore the possibility of new microbial contamination, for example as early as in the second heating module.
EP-A 1 896 245 A2 describes a method in which, prior to the heating, a gaseous sterilization agent is introduced into a cold preform and condenses there. A problem here is ensuring complete formation of condensate on the entire inner surface of the preform since the inflowing hot sterilization agent increases the temperature of the inner wall of the preform. Furthermore, here too the sterilization agent, after evaporation thereof in the region of the heating system, leaks in an uncontrollable manner out of the preform within the heating system. The problem of new microbial contamination in the heating system likewise continues to exist.
The arrangement of a sterilization unit between a heating system and the blow molding module is described in WO 2010/020530 A1. In the case of this method, the amount of sterilization agent admitted into the region of the blow molding unit can be predicted only with difficulty. Furthermore, the amount of sterilization agent escaping into the environment cannot be controlled and corresponding contamination is not excluded. The problem of new microbial contamination, for example after the blow molding, is also not effectively countered here.
It is also known to use radiation sources for sterilization purposes. The use of UV emitters for sterilization tasks is generally known, for example, from DE 295 03 830 U1. A space which is enclosed by a protective housing is intended to be sterilized by irradiation with UV light. This document does not disclose sterilizing preforms or containers, or blow molding machine elements coming into contact therewith. DE 10 2008 038 143 A1 discloses that UV radiation emitters can be used for sterilizing the outer wall of preforms.
DE 10 2007 017 938 B4 discloses the use of radiation emitters for sterilizing the inner surfaces of preforms. For this purpose, a sterilization probe which carries a radiation emitter is inserted into the preform to be sterilized. WO 2010/012915 A1 and EP 2 138 298 A2, in which, for internally sterilizing a preform, a radiation source is likewise inserted into the mouth of the preform, also show comparable prior art. It is stated in the last-mentioned document that a plurality of sterilization units should be provided, namely at least one upstream of the unit in which the preforms are formed to form containers, and at least one downstream thereof. It is considered to be disadvantageous in particular in the last-mentioned prior art that a high outlay on apparatus is required.
A fundamental problem is that preforms or containers sterilized in a sterilization station have to be protected from new microbial contamination on their further transport route. It is an aim to be able to decant a germ-sensitive beverage under aseptic filling conditions. This requires at least one germ-free container. To this extent, it is not sufficient only to sterilize the preform or the blow molded container. To avoid new microbial contamination, at least those elements of the blow molding machine which, after the sterilization of the preform, come into contact with the preform, also have to be kept sterile. In the prior art, for example in EP 2 138 298 A2, this problem is countered by the fact that a sterile housing is provided which surrounds the blow molding machine and has to be kept sterile with a considerably outlay. The interior of said sterile housing is sterilized with all of the equipment located therein and then the entire interior is protected against new microbial contamination. The outlay on construction and energy are enormous and contribute considerably to the production costs. In addition, the same document proposes undertaking a second sterilization step after the blow molding operation. This also means a considerable additional outlay.
A better solution for preventing new microbial contamination is disclosed in WO 2012/083910 A1. A sterile space surrounding the blow molding machine and optionally further treatment stations, such as fillers or closers, is not provided there; instead, a channel which conducts sterile gas and along which the preform or the blow molded container is guided, is shown there. The channel is provided with outlet openings out of which the sterile gas can flow in order to produce a corridor acted upon with sterile gas. The preform or the container is guided in said sterile gas corridor and, in the process, is acted upon and flowed around by the sterile gas. New microbial contamination is thereby effectively prevented. Nevertheless, a further outlay is also required here.